System and method for monitoring a site using time gap analysis

Abstract

A method for monitoring a site includes calculating a learned threshold time based on a statistical analysis of lengths of time between sensor firings of one or more sensors. A first sensor firing is detected from the one or more sensors. The length of time that has elapsed since the first sensor firing is measured. The length of time that has elapsed since the first sensor firing is compared with the learned threshold time. An alarm condition is generated when the length of time that has elapsed since the first sensor firing exceeds the learned threshold time and no second sensor firing has been detected since the first sensor firing.

1 . A method for monitoring a site, comprising the steps of: 
 calculating a learned threshold time based on a statistical analysis of lengths of time between sensor firings of one or more sensors;    detecting a first sensor firing from the one or more sensors;    measuring the length of time that has elapsed since the first sensor firing;    comparing the length of time that has elapsed since the first sensor firing with the learned threshold time; and    generating an alarm condition when the length of time that has elapsed since the first sensor firing exceeds the learned threshold time and no second sensor firing has been detected since the first sensor firing.    
     
     
         2 . The method of  claim 1 , wherein when the second sensor fires before the learned threshold time has elapsed, the steps of detecting, measuring, comparing and generating are repeated.  
     
     
         3 . The method of  claim 2 , wherein the learned threshold time is updated based on statistical analysis of lengths of time between the subsequent sensor firings.  
     
     
         4 . The method of  claim 1 , additionally comprising the step of alerting one or more caregivers or responsible persons of the alarm condition when an alarm condition has been generated.  
     
     
         5 . The method of  claim 1 , additionally comprising the step of summoning an emergency response to the monitored site when an alarm condition has been generated, the emergency response including medical assistance when appropriate.  
     
     
         6 . The method of  claim 1 , wherein the learned threshold time is calculated based on trend analysis of lengths of time between previously observed sensor firings.  
     
     
         7 . The method of  claim 1 , wherein the learned threshold time is based on the site monitored or from one or more other monitored sites.  
     
     
         8 . The method of  claim 1 , wherein the learned threshold time is calculated based on statistical analysis of lengths of time between previously observed sensor firings comprising the steps of: 
 recording a set of time gaps equaling the lengths of time between previously observed sensor firings;    calculating an average for the set of time gaps;    calculating a standard deviation for the set of time gaps;    setting the learned threshold time as the average time plus a multiple of the standard deviation.    
     
     
         9 . The method of  claim 8 , wherein said multiple is 2 times the standard deviation.  
     
     
         10 . The method of  claim 8 , wherein said multiple is 3 times the standard deviation.  
     
     
         11 . The method of  claim 1 , wherein the learned threshold time is set to a default threshold time when the number of previously observed sensor firings is zero or an insufficient number to calculate a statistically significant threshold time.  
     
     
         12 . The method of  claim 11 , wherein the number of previously observed sensor firings sufficient to calculate a statistically significant threshold time is set as the number of previously observed sensor firings observed over a period of seven days or a number of days that cover normal activities that are periodic in nature.  
     
     
         13 . The method of  claim 1 , wherein the steps of detecting, measuring and comparing time gaps are temporarily suspended and resumed.  
     
     
         14 . A system for monitoring a site, comprising: 
 one or more sensors installed within the monitored site for sensing activity and firing when activity is sensed; and    a data processing unit for: 
 calculating a learned threshold time based on a statistical analysis of lengths of time between sensor-firings of one or more sensors;  
 detecting a first sensor firing from the one or more sensors;  
 measuring the length of time that has elapsed since the first sensor firing;  
 comparing the length of time that has elapsed since the first sensor firing with the learned threshold time; and  
 generating an alarm condition when the length of time that has elapsed since the first sensor firing exceeds the learned threshold time and no second sensor firing has been detected since the first sensor firing.  
   
     
     
         15 . The system of  claim 14 , wherein the one or more sensors are motion detectors.  
     
     
         16 . The system of  claim 14 , wherein the data processing unit is a base station in communication with the one or more sensors installed within the monitored site.  
     
     
         17 . The system of  claim 16 , wherein the base station is in communication with a service center and an alarm condition generated by the base station is communicated to the service center.  
     
     
         18 . The system of  claim 14 , wherein the data processing unit is located at a service center and is in communication with the one or more sensors installed within the monitored site.  
     
     
         19 . The system of clain  14 , wherein one or more caregivers is alerted of the alarm condition when an alarm condition has been generated.  
     
     
         20 . The system of  claim 14 , wherein an emergency response is summoned to the monitored site when an alarm condition has been generated, the emergency response including medical assistance when appropriate  
     
     
         21 . The system of  claim 14 , wherein the learned threshold time is calculated based on trend analysis of lengths of time between previously observed sensor firing signals.  
     
     
         22 . The system of  claim 14 , wherein the learned threshold time is calculated based on statistical analysis of lengths of time between previously observed sensor firing signals, comprising the steps of: 
 recording a set of time gaps equaling the lengths of time between previously observed sensor firing signals;    calculating an average for the set of time gaps;    calculating a standard deviation for the set of time gaps; and    setting the learned threshold time as the average time plus a multiple of the standard deviation.    
     
     
         23 . The system of  claim 22 , wherein said multiple is 2 times the standard deviation.  
     
     
         24 . The system of  claim 22 , wherein said multiple is 3 times the standard deviation.  
     
     
         25 . The system of  claim 14 , wherein the learned threshold time is set to a default threshold time when the number of previously observed sensor firing signals is zero or insufficient to calculate a statistically significant threshold time.  
     
     
         26 . The system of  claim 25 , wherein the number of previously observed sensor firing signals sufficient to calculate a statistically significant learned threshold time is set as the number of previously observed sensor firing signals observed over a period of seven days.  
     
     
         27 . The system of  claim 14 , wherein the data processing unit temporarily suspends the detecting, measuring and comparing and resumed.  
     
     
         28 . A computer system comprising: 
 a processor; and    a program storage device readable by the computer system, embodying a program of instructions executable by the processor to perform method steps for monitoring a site, the method comprising:    calculating a learned threshold time based on a statistical analysis of lengths of time between sensor firings of one or more sensors;    detecting a first sensor firing from the one or more sensors;    measuring the length of time that has elapsed since the first sensor firing;    comparing the length of time that has elapsed since the first sensor firing with the learned threshold time; and    generating an alarm condition when the length of time that has elapsed since the first sensor firing exceeds the learned threshold time and no second sensor firing has been detected since the first sensor firing.    
     
     
         29 . The computer system of  claim 28 , wherein when the second sensor fires before the learned threshold time has elapsed, the steps of detecting, measuring, comparing and generating are repeated.  
     
     
         30 . The computer system of  claim 29 , wherein the learned threshold time is updated based on statistical analysis of lengths of time between the subsequent sensor firings.  
     
     
         31 . The computer system of  claim 28 , additionally comprising the step of alerting one or more caregivers or responsible persons of the alarmi condition when an alarm condition has been generated.  
     
     
         32 . The computer system of  claim 28 , additionally comprising the step of summoning an emergency response to the monitored site when an alarm condition has been generated, the emergency response including medical assistance when appropriate  
     
     
         33 . The computer system of  claim 28 , wherein the learned threshold time is calculated based on trend analysis of lengths of time between previously observed sensor firings.  
     
     
         34 . The computer system of  claim 28 , wherein the learned threshold time is based on the site monitored or from one or more other monitored sites.  
     
     
         35 . The computer system of  claim 28 , wherein the learned threshold time is calculated based on statistical analysis of lengths of time between previously observed sensor firings comprising the steps of: 
 recording a set of time gaps equaling the lengths of time between previously observed sensor firings;    calculating an average for the set of time gaps;    calculating a standard deviation for the set of time gaps;    setting the learned threshold time as the average time plus a multiple of the standard deviation.    
     
     
         36 . The computer system of  claim 35 , wherein said multiple is 2 times the standard deviation.  
     
     
         37 . The computer system of  claim 35 , wherein said multiple is 3 times the standard deviation.  
     
     
         38 . The computer system of  claim 28 , wherein the learned threshold time is set to a default threshold time when the number of previously observed sensor firings is zero or an insufficient number to calculate a statistically significant threshold time.  
     
     
         39 . The computer system of  claim 38 , wherein the number of previously observed sensor firings sufficient to calculate a statistically significant threshold time is set as the number of previously observed sensor firings observed over a period of seven days or a number of days that cover normal activities that are periodic in nature.  
     
     
         40 . The computer system of  claim 28 , wherein the steps of detecting, measuring and comparing time gaps are temporarily suspended and resumed.